The present invention relates to improved disposable articles such as diapers, incontinent products, disposable garments, feminine hygiene products, and the like.
Disposable baby diapers are often used in conjunction with powders or oils applied by the parent onto the baby. Quite often, the powder or oil contaminates the outer backsheet portion of the diaper. Typically, the powder or oil is transferred to the diaper backsheet by the parent's hands or from the baby. A persistent problem with such powder and oil contamination is that conventional adhesive tab closures used with diapers are adhered onto the outer backsheet portion of the diaper and do not adequately adhere to surfaces contaminated with talc or particularly oil.
U.S. Pat. No. 4,163,077 proposes a diaper closure system wherein the adhesive used on the fastening tab is a particular blend of a synthetic block copolymer and a blend of solid and liquid polyterpene type tackifiers. This adhesive provides a limited ability to adhere to talc or powder contaminated diaper surfaces, such as polyethylene backsheets typically employed in commercial diaper constructions. However, this adhesive composition does not address the problems of adhering to an oil-contaminated diaper substrate.
The problem of adhering to oil-contaminated surfaces with conventional pressure-sensitive adhesives is addressed in U.S. Pat. No. 3,991,002, which describes a method for improving the adhesion of normal pressure-sensitive adhesive tapes to oily or greasy substrates by treating the oil-contaminated substrate with a primer. This primer comprises a rubbery phase of a A-B-A triblock copolymer, such as a styrene-butadiene or styrene-isoprene block copolymer, and a resin phase comprised of a resin compatible with the conjugated diene portion of the block copolymer and a resin compatible with the monovinyl aromatic hydrocarbon portion of the block copolymer (i.e., styrene). These components are placed in a solution, then applied as an aerosol to render the oil-contaminated surface stable for subsequent adhesion. This patent states that the conventional approach to adhering to oil-contaminated surfaces is a complicated and time-consuming clean-up procedure. However, the primer solution proposed in this patent is still impractical for most consumer applications and particularly in a diaper being applied to a baby.
The present invention is addressed at solving the problems identified above. Particularly, the invention is directed at providing a diaper construction provided with a reinforced tape adhesion zone that has the property of oil-contamination tolerance.